This spell functions like symbol of death,
except that using the material component, you scribe a symbol of
striking so it fills a 5-foot square. Once triggered, the symbol of
striking glows and lasts for 10 minutes per caster level or until it has made a number of attacks of opportunity
equal to your level, whichever comes first. When triggered, the symbol
threatens its area and the area around it as if it were a Medium
creature wielding a magic version of the weapon you used as the material
component. Using your caster level + 1 + your Intelligence modifier (magus, witch, wizard) or Wisdom modifier (cleric) or Charisma modifier (oracle, sorcerer) as its attack bonus, the symbol can make a number of attacks of opportunity each round equal to 1 + the same ability score modifier you used to determine its attack bonus. It gains a bonus on damage rolls equal to the same ability score modifier you used to determine its attack bonus.
A shadowy version of you wielding the material component appears to
make these attacks. The symbol attacks any non-attuned creature that
provokes an attack of opportunity from the symbol. However, when the symbol first attacks a creature, the symbol must overcome that creature’s spell resistance
or be rendered unable to harm it. The symbol never again attacks such
creatures. Further, when the symbol first attacks a creature, a
successful Will saving throw allows the creature to see the shadow nature of the attacks and take half damage when such attacks hit.

Symbol of striking can be made permanent with a permanency spell by a caster of 13th level or higher for the cost of 10,000 gp.